What’s a snow squall?
A snow squall—a brief yet intense blizzard-like storm—approaching Slate River Valley near Crested Butte, Colorado. (Flickr user: Jeffrey Beall /)Last December, television reporter David Jones tweeted a time-lapse of an impenetrable cloud of snow overtaking Manhattan and swallowing it whole by the end of the 32-second clip. “Run!” one person responded to the video, which has now been viewed about 350,000 times. “Produced by Stephen King,” another joked, joined by more than a few references to the Game of Thrones’ “Winter is coming” tagline.About a minute before Jones posted the video, the National Weather Service inundated cellphones around the New York metro region with a rare emergency alert for a “Snow Squall Warning.” It was the second time New Yorkers received such a push alert, but the Northeast has long experienced the short-lived burst of heavy snowfall characteristic of a snow squall. “We’re more used to precipitation in wide swaths:...